Multiple switch-board



2 Sheets-Sheet 1.

(No Model.)

M. G. KELLOGG.

MULTIPLE SWITCH BOARD.

No. 386,887. Patented July 31, 1888.

H LVV wW WW W w WWWWW v 1:

N. PETEHS. PlwlvL ibompher. Wnhillgion. D. C.

(No Model.) 2 Sheets-Sheet 2.

' M. G. KELLOGG.

MULTIPLE SWITCH BOARD.

No. 386,887. Patented July 31, 1888.

N. PETERS. Phulo-Liflwg'rapber, Within-13100, D. C,

.Nrren STATES i MILO G. KELLOGG, OF HYDE PARK, ILLINOIS.

MULTlPLE SWITCH-BOARD.

SPECIFICATION forming part of Letters Patent No. 386,837, dated July 31, 1888.

Application filed August 23, 18257. Serial No. 247,641.

To all whom, it may concern.-

Be it known that I, MILO G. KuLLoGG, of Hyde Park, Illinois, have invented certain new and useful Improvements in Multiple Switch-Boards for Telephone-Exchanges, of which the following is a full, clear, concise, and exact description, reference being had to the accompanyingdrawings, forming a part of this specification.

My invention relates to a telephone-exchange system in which the subscribers lines are metallic circuits, and in which one of the wires ofa metallic circuitis normally grounded at the central office and the other wire is normally open at the central office.

It consists, first, of a multiple-switch-board system of operating an exchange and testing at any board to determine whether any given line is in use, which I shall hereinafter describe and claim in detail.

It consists, secondly, of an arrangement of subscribers station apparatus, which I shall hereinafter describe and claim in detail, said apparatus being applicable to said multipleswitch board system mentioned above, and to other systems of telephone-exchange switchboards.

In my system I use loop switch-plugs having two insulated metal pieces and two insulated flexible conductors attached to said pieces. I place as many switch-boards in the central office as are found necessary or desirable in order to properly answer the calls and connect and disconnect the subscribers lines. On each board I place for each telephone-line which centers at the officea springjack or similar switch having two insulated contactpoints normally in contact,and a third contact point or piece normally insulated from the others except by line-colmections, said switch being adapted to receive a switch-plug, and when the plug is inserted to disconnect the switch-points which are normally in contact and connect one of them to one of theinsulated metal pieces of the plugs, and at the piece mentioned above is also placed and arranged so that the operator may at will apply (No model.)

a test-plug or other test device to it. Aseparate test bolt or piece might, however, be used for each line for each board, providingitwere connected to the open end of the line.

The switches of a line on the different boards may be called a sericsofswitches, and the test-pieces ofa line, or the contact points or pieces when used as tcstpicces, may be called a series of test bolts or pieces.

Figures l and I" of the drawings are front views of sections of two multiple switchboards to which the same wires are connected. Fig. 2 shows a diagram of the boards and the circuits and connections necessary to operate them when used in connection with the operators cord system and the subscribers station apparatus, hereinafter described. Fig. 3 is a diagram of the operators cord system. Fig. 4 is a diagram of the subscribers station apparatus, and Fig. 5 is a modification of part of the operators cord system shown in Fig. 3.

In the drawings like parts and apparatus are indicated by the same letters of reference.

In Fig. 2, A is a sectional viewof theswitchboard shown in Fig. 1, as indicated by line (I e, and A is a sectional view of the switchboard shown in Fig. 1", as indicated by linede.

a I) represent rubber strips, of the shape substantially as shown, on which the metal parts of the spring-jack switches are mounted. These strips may be of a length to receive any convenient. number of spring-jack parts. H, &c., are square holes through the fronts and at the edges of the strips, adapted to receive the switch-plugs. The contact-springs g g, &c., are mounted to the rear of and are parallel to the holes Z Z to which they belong, as shown. The contact-points h h, &c., corresponding to the contact-springs, pass through the rubber strips and have connectingpieccs h h, 850., as shown. jj, 850., are the contact-pieces of the switches, insulated from the rest of the parts, except by line-wires, each adapted to connect one side of its line to one of the contact-pieces of the plug when the plug is inserted into the switch, and also to be a testbolt of its line at its board.

The switch-plugs are substantially as shown in Fig. 3, and as will hereinafter be described.

The several parts mentioned above are so shown.

made, shaped, arranged, and adjusted that when a switch-plug is inserted into any of the switch-holes it raises the spring in the rear of the hole from the contact-point, (on which it normally rests.) and the spring is connected to one of the contact-pieces of the plug, while the other contact-piece ofthe plug is connected to the contact-piece j of the switch which is being used.

Each section of a rubber strip, with its contact-spring, contact-point, contact-piece, and the hole, all arranged and operating as above, may be considered as a spring'jack switch. It is not necessary that the switch-holes should be square, as they may be made to conform to the shapes and arrangement of the parts used.

The circuits and connections of a subscribers line to its series of switches are as follows, and as shown.

I have marked the ingoing and the outgoing wires of such a line wire No.1 and wire No. 1".

s and s are the switches for the two lines on the two boards.

\Vire No. 1, after entering the office, passes first to springg ofswitch s, and thence, through contact-point h and connecting-piece h of that switch and wire 3, to spring 9 of switch 8, and thence, through contact-point h and connecting'piece h ofthat switch and wire 8, to the line-annunciator, and thence to the common ground-wire and ground.

lVire No. 1" is connected to the contactpiecesjj of switches s and s by wire 8 and its branches, (also marked s,) as shown.

I have marked the two wires of another subscribersmetallic-circuitlinewire No. 2 and wire N0. 2, and they are connected to their Switches 1' and r, as shown, and similar to the above. In like manner would the other lines of the exchange be connected to theirswitches. Other boards might be added to the exchange, and the connections of the lines to their switches would be similar to the above and such as would be evident to those skilled in the art.

In the operator's system of cords shown in Fig. 3 only one pair of cords, with its plugs, switch-keys, clearing-out annunciator, tele phone, and calling battery or generator is Other pairs with their parts could be added and connected in a manner which will be apparent to those skilled in the art. One system of pairs of cords is placed at each board for an operator, and the parts are so mounted that the operator can conveniently operate the board.

D D represent a pair of'plugs in sectional View.

n is the rubber insulation of the plug. m is one of its contact-pieces, and m is the other contact-piece. The contact-pieces m mextend to the bottom of the plug, as shown, and are adapted to rest normally, or, when the plug is not in use for switching, on the metal strip 0, which thereby temporarily connects asses? them together. Weights, as is usual, or similar devices, may be used to bring the plugs into contact with the strip and form a good connection.

Y is a loopingiu switch having two pairs of contact-bolts, y y and z 2, on which the operator may at will place thelevers of the switch.

1) is the clearing-outannunciator of the pair of cords. 7c is a looping-in key constructed, substantially as shown, whereby the operator may at will loop her calling-generator into the circuit of a pair of cords.

B is the operators calling generator or battery. t is her telephone, and 7c is a test-key. The cords have two insulated conductors, as shown, and should be long enough so that the operator may connect any plug with any switch at her board. Each operator needs only one calling-generator, one telephone, and one test-key for her system. as many looping-in switches and as many looping-in keys as she has pairs of cords. The circuits aresubstantially as shown. The testing-key may be dispensed with, and in that She should have case the wire which branches off from one of in Fig. 4, 1 is the telephone-switch, 2 is the.

signal-bell, 3 is the calling-generator, 4 is the hand-telephone, 5 is the transmitter, 6 I

is the primary, 7 is the secondary of the induction-coil, and 8 is the transmitter battery. These parts may be the usual forms of apparatus and are connected as shown, or in other known ways, except the calling-generator, which is modified and connected as shown. Wire No. l" and wire No. 1 (shown in this figure) are two wires of a circuit. The generator has an automatic device, (shown in the drawings,) by which,when the crank is not in motion, the wire of the armature is shunted, and the line is disconnected from the ground at the subscribers station, and when it is turned or operated the shunt is automatically removed from the armature and the line is temporarily connected to the ground. The reason for this will hereinafter be apparent.

The automatic device shown is a modification of a form very generally used, the modification being substantially in the arrangement of the contacts. It contains a V-shaped attachment to the hub of the driving-wheel, a pin in the shaft,which engagesin this V-shaped arrangement, and a spring which presses against the wheel and brings the pin normally in the center of the V arrangement. tact-points and the circuits are substantially as shown and as will produce the results described above. Other automatic devices may be used and modified so as to produce these results. A common key or switch might be used and operated by the hand of the subscriber to ground the line while he is sending in the signal. The generator should be con- The conand the battery.

nected so that the temporary ground is made between the normally-open end of the sub scribers line and the armature coil.

It will be noticed that the transmitter-battery is in the line-circuit and that it is closed to the transmitter and to the primary of the inductioncoil when the telephone-switch is in position for the telephone to be used. The transmitterbattery also acts as a testbattery for its line, as will hereinafter appear.

The operation of the system is as follows: \Vhen a subscriber desires to call, he turns the crank ofhisgenerator,and thereby temporarily connects his line with the ground, and, sending a calling-currentover it, operates the lineannunciator at the central oifice. He then removes his telephone from its switch, and the operator at the central ofiice places D (one plug of a pair of plugs) in the switch of the line where a call is indicated, and, placing the levers of the switch Y corresponding to this pair of plugs on its bolts y 1 the subscriber and the operator are connected together in metallic circuit for conversation. When the operator finds out what line is wanted, she places m of the other plug of the pair on the contact-piece of the switch of the line wanted for a test, pressing meanwhile on the key k. If the line tested is not in use, there will be a complete circuit from the ground at the central office, through the operators telephone, thence through the contact-piecej and the line, through the subscribers station battery, back to the central office, and to ground. The battery being thus closed through the operators telephone, she will hear a click in it and will know that the line is not in use. She will then place the plug in the switch, and, moving the levers of the switch Y (corresponding to the pair of plugs used) so that they rest on 2 2, she will press on the key It and temporarily loop her calling-generator into the circuit. Vhen she removes the pressure from the key 7;, the clearing-out annunciator will be in the circuit. Thus the subscribers are connected together in metallic circuit, are called, and are left for conversation with a clearing-out annunciator in their circuit. If, when the operator made thetest, as above described, the line tested had been switched at another board, it would have been disconnected from the ground and she would not have heard the click in her telephone, as therewould not then have been a complete circuit through her telephone She would thus have known that the line was busy, and she would not have completed the connection.

The operator can always, by moving the levers ol' the switch Y to y 3 listen on her telephone to see whether the subscribers are through conversation. \Vhen they are through conversation, either one can turn the crank of his generator and send a clearing-out signal through their metallic circuit, which will operate the clearing-out annunciator left in the generator will of course ground the circuit while he is sending the signal; but this will not prevent its operation.

The subscribers telephone should be on his switch when his line is not in use, thereby opening the local-battery circuit and shunting the telephone.

When a pair of plugs are not in use, thelcvers of the switch Y corresponding to them Should rest on 2 z.

I claim as my invention and desire to secure by Letters Patent 1. In a telephone-exchange system, a metallic-circuit telephone-line normally open at one end at the central office and normally grounded at the otherend at the central office, and there only, in combination with a battery in the circuit of the line at the subscribers station, a switching device containing a pair of contact points or pieces in the circuit of the line at the central ofiice,adapted to remove the ground from the line when it is switched with another line for conversation, a testrcceiving instrument at the central oifice, and a switch testing-plug or contact-piece connected to one side of the test receiving instrument, and adapted, at the will of the operator, to connect the test-receiving instrument grounded on one side to the normally open end of the line on the other side, and thereby determine whether the line is switched for conversation.

2. In a telephoneexchange system, two or more switch-boards at the central oflice, and metallic circuit-lines connected to them, each line being normally open at one end and connected at that end to each ofthe switch-boards and normally grounded at its other end at the central office, and there only, and each line having a battery in its circuit, in combination with switching devices, one for each line at each board, each containing a pair of contact points or pieces in the circuit of the line, adapted to remove the ground from its line when the line is switched for conversation, test-receiving instruments, one at each board, and switch-testing plug or contact-piece connected to one side of the test-receiving instrument at each board, whereby the operator at any board may connect her test-receiving instrument, grounded on one side, to the normally-open end of any line on its other side, and determine whether the line is switched for conversation.

3. In atelephonc exchange system, a metallic'circuit telephone-line normally open at one end at the central otlice and normally grounded at the other end, and there only, and having a battery in its circuit, in combination with a generator in the circuit of the line at the subscribers station, an annuuciator in the ground wire or connection at the central office, a switching device adapted to ground said line at the subscribers station between its normally-open end and the generator when the generator is being operated, a switching decircuit. The automatic attachment of the l vice containing a pair of contact points or ICC ITO

pieces in the circuit of the line at the central office adapted to disconnect the line from the ground when it is switched for conversation, a test-receiving instrument at the central ofiice, and a switch-testing plug or contact-piece connected to one side of the testreceiving instrument adapted, at the will of the operator, to connect the test-receiving instrument, grounded on one side, to the normally-open end of the line on the other side, substantially as and for the purpose set forth.

I. In a telephone-exchange system, a metallic-circuit telephone-line normally grounded at the central office and having a calling-annunciator in its ground wire or connection, and a switching device containing a pair of contact points or pieces in the circuit of the line at the central office adapted to remove said ground and to connect said line with another line in metallic circuit with a clearingout annunciator in the circuit, in combination with a calling-generator at the subscribers station, and a switching device having two pairs of contact-points, said switching device being operated in one direction by a spring, and in the other direction by the force which actuates the generator, one pair of said points switching the generator,when it is being operated, into circuit with the line, and the other pair then grounding the line with the generator between this ground and the office ground, the subscriber being thereby enabled to oper ate the calling-annunciator when it is connected to his line and the clearing-out annunciator when it is looped into the metallic circuit, substantially as set forth.

5. In a telephone-exchange system, a metallic-circuit telephone-line grounded on one of its sides or branches at the central office, and grounded there only, in combination with a battery in the circuit of the line at the subscribers station, a switching device containing a pair of contact points or pieces in the circuit of the line at the central office adapted to disconnect said side or branch from the ground while the line is switched with another line for conversation, a test-receiving instrument and switch-testing plug or contact-piece connected to one side of the test-receiving instrument adapted, at the will of the operator, to connect said test receiving instrument, grounded on one side, on its other side to the other branch of the line open to the ground, substantially as and for the purpose set forth.

6. In a telephone-exchange system, a metallic-circuit telephone-line grounded on one of its sides or branches at the central oflice and disconnected from the ground at the subscribers station, in combination with a battery in the circuit of the line, a switching de' vice containing a pair of contact points or pieces in the circuit of the line at the central office adapted to disconnect said side or branch from the ground while the line is switched with another line for conversation, a test-receiving instrument, and a switch-testing plug or contact-piece connected to one side of the test-receiving instrument adapted, at the will of the operator, to connect saidtest-receiving instrument, said instrument being grounded on its other side, and said switch-testing plug being adapted, at the will of the operator, to connect with the other branch of the line, which is disconnected from the earth, substantially as set forth.

' 7. In a telephone-exchange system, a metallie-circuit line normally disconnected from the ground at the subscribers station and normally connected on one ofits sides or branches with a ground wire or connection at the central office, a calling-annunciator in said ground wire or connection, and switching devices or means containing a pair of contact points or pieces in the said side or branch, and another contact point or piece connected to the other side or branch at the central olfice adapted to temporarily disconnect said line from said ground wire or connection and to connect it in metallic circuit with another line, in combination with a calling-generator at the subscribers station in said line and switching devices or means containing a pair of contactpoints normally open. one of which is connected with the ground and the other one to the line between the generator and the nor mally-open end of the line, whereby the sub scriber, while operating said generator, grounds said line with the generator between the ground and said office ground wire or connection, substantially as and for the purpose set forth.

' 8. In a telephone-exchange system, a metallie-circuit telephone-line normally dise0n-' nected from the earth at the subscribers stat on and normally grounded on one side only at the central ofice and a switching device containing a pair of contact-points in the circuit of the line at the central office, in combination with a generator in the circuit of the line at the subscribers station while operated, a switching device at the subscribers station containing a pair of contact-points normally open, and an annunciator in the circuit of the line at the central office, said normally-open contact-points being closed while the generator is operated, one of them being connected to the subscribers ground and the other to the line with the generator and annunciator between it and the office ground, substantially as set forth.

MILO G. KELLOGG. Witnesses:

MILTON HEAD, CALVIN DE WOLF.

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